Whenever discussing Indian Philosophy, a note on the ‘Sources of knowledge’ (in Sanskrit, Pramāna) is unavoidable. Philosophy deals with external objects. So getting details about the external objects is crucial to formulate philosophic theories. There are various ways or means to know the outside objects. These means are commonly called as Pramāna or ‘Sources/methods of knowledge’. Pramānas collect information from the ‘knowledge sources’ in a peculiar way and it will have a unique data communication or conveying style
Each Indian philosophical system admits different number of Pramānas. Also it is to be noted that, Nyaya system is the foremost sect, which pays utmost importance to the Pramānas. Their particular interest is in Inference and Syllogism. While Advaita Vedanta approves six Pramānas, Buddhists approve only two. But it is a common practice among philosophy schools to group several Pramānas into a single group. Anyway three Pramānas are approved by almost all philosophical sects of India and they are – Perception, Inference and Testimony.
Pratyaksha or Perception:-
In perception, we use our sense organs to collect data from the external world. Perception is able to give us a concrete and distinct knowledge about an object and in this sense, it is slightly different from Inference, in which the knowledge is getting always indirectly.
Perception can be internal or external. In external perception, usually our external organs perceive the objects and hand over the information to the mind. Then Mind communicates this with the Atman. The functioning of Atman – mind – sense organs trio is different for each philosophy systems. Apart from external perception, there is ‘internal perception’. We comprehend the pleasure, pain, desire etc. through the internal perception. Here Atman gets knowledge about the mood of mind directly from the Mind. So it is very quick and determinate in nature.
There are commonly two classifications about perception regarding certain philosophical sects, including Advaita Vedanta. They approve two stages in apprehending an object. They are indeterminate perception (Nirvikalpaka) and Determinate perception (Savikalpaka). As per this every determinate perception is preceded by a indeterminate perception. In indeterminate perception perceiver does not identify the kind and quality of the object. Perceiver only gets a vague idea of something that is to determined and known next. But in determinate (savikalpaka) perception perceiver get the full details about the object including the object’s generic and specific attributes.
Not all philosophical sects have approved the indeterminate knowledge. Ramanuja and madhva acarya have discarded the indeterminate knowledge theory. They contend that all knowledge is determinate only. And according to certain sects, like advaita Vedanta, perceptive knowledge is self – manifest and self valid. That is, perceptive knowledge is known by itself and the validity of knowledge is inherent in the knowledge. Only external causes can make the knowledge false. But Nyaya system has different opinions in these cases. They contents that the knowledge need another knowledge to manifest and the validity of knowledge is determined by external causes. That is, validity of knowledge is extrinsic.
Anumāna or Inference:-
It is a process by which we gets the knowledge of an object, through its mark. That is, the knower gets the knowledge from another knowledge. Anumana is based on the invariable concomitance of two things, like fire and smoke. This invariable concomitance between two things is known as ‘vyapti’. It is not just the presence of an object when its ‘mark’ is present, but also the non-present of an object when the ‘mark’ is absent; i.e. concomitance between two things at all time. If the first criterion is met then the second criterion must be present there. Also when the first criterion is absent, the second criterion must not present there. There should not be any contradiction to the above mentioned relations, from the other factors. This kind unbreakable relation, called ‘vyapti’, must exist for a fault proof ‘anumana’ to work.
There are two types of inference. First – ‘inference for himself’, in which one argues with himself and find out the unperceived thing from the perceived ‘mark’. Second – ‘inference for others’, in which he tries to convince others, the inferential relation or truth that he understood, in an argument style. This is known as syllogism, for which an example is given below.
“Whatever has smoke has fire, such as a kitchen.
The hill has smoke.
Therefore the hill has fire.”
Major Indian philosophical sects hold three member syllogisms, except Nyaya, which advocate five member syllogisms as follows:
“The hill has fire.
Because it has smoke.
Whatever has smoke has fire, such as a kitchen.
The hill has smoke such as always accompanied by fire.
Therefore the hill has fire.”
Indian syllogism is a combined deductive – inductive process of reasoning. Observation and generalization are processes involved in it. B N Seal in this ‘The positive sciences of the ancient Hindus’, has rightly said:
“Anumana is the process of ascertaining, not by perception or direct observation, but through the instrumentality or medium of a mark, that a thing possesses a certain character. Inference is therefore based on the establishment of an invariable concomitance between the ‘mark’ and the character inferred. The Hindu inference is therefore neither merely formal not merely material, but a combined Formal – Material Deductive – Inductive process…… this formal – material deductive – inductive process thus turns on one thing – the establishment of the invariable concomitance between the ‘mark’ and the character inferred – in other words, an inductive generalization.”
D M Dutta further adds in his ‘The six ways of knowing’:
“… The necessity of classifying inference into the deductive and inductive also did not arise, because for the Indian logician no syllogism was of any value unless based on a universal major established through induction; consequently, the processes of induction and deduction blended together to constitute a syllogism”
The ‘inference branch’ of pramana, in Indian philosophy, has many members. Certain philosophical sects, consider certain pramanas of other philosophy system as ‘inference’ in their own. For example Advaita Vedanta has six pramanas – perception, inference, comparison, postulation, non-apprehension and verbal testimony. Though other philosophy systems approves these all in principle, they don’t consider ‘comparison, postulation and non-apprehension’ as separate pramanas. Instead they include them in ‘inference’ section of their own pramana list. Thus Viaseshika, having only perception and inference as pramanas, considers comparison and postulation as only ‘inference; in their own system.
Thus inference is a pramana which is approved by all philosophy systems of India, except Carvakas.
Sabda or Verbal Testimony:-
Perception and inference can give us knowledge which is in the phenomenal plane. This is a limitation of them, though they are considered at par with ‘Sruti’ in this plane. Sruti injections and sense perceptions cannot contradict each other, in the phenomenal knowledge area and so sense perceptions and inferences have as much validity as Sruti, there. If a Sruti injection is not found to be in accordance with a perceptual fact, in the relative phenomenal world, then the real purport of the Sruti passages must have been misinterpreted and this need to be corrected. In short, Sruti passages and perception/inference cannot contradict each other, in the phenomenal level knowledge.
Unlike perception and inference, verbal testimony, which includes ‘Sruti’, is the only source of knowledge that can give knowledge about the transcendental knowledge like knowledge about Brahman. Verbal testimony presents knowledge that is supra sensual; i.e, knowledge that is beyond the realm of sense organs. On the other hand, perception and inference are the sources of knowledge in the phenomenal place and so they cannot help to get the supra-sensual knowledge about Brahman.
Verbal testimony as a source of knowledge is not against reason. As a matter of fact, we cannot gather knowledge from every area. Also our knowledge in a particular field may not be in its highest possible level. This situation compels us to listen to the genius people’s opinion and consider it seriously. The verbal testimony as a source of knowledge arises here. It can give us knowledge that is not present in front of us in the phenomenal world. The problem of knowing the ultimate truth, especially if we were a beginner in that field, is effectively solved here. What all we need to find a teacher and get the knowledge about Brahman from him. The verbal testimony or authority is very much important thus.
Perception and inference are inefficient to provide the knowledge that is revealed to the ancient Hindu sages. They have realized the supreme status which a common man may achieve by austerity and knowledge. They have conveyed the procedure to the future generations. Vedic literature is considered as such texts and they are considered as the verbal testimony by many Indian philosophical systems. Only Carvakas denies the verbal testimony as a pramana, totally. All others have accounted it as a pramana in one way or other.
Problems with the Perception:-
Perceptive knowledge may be false. We perceive earth as flat, but in fact it is spherical. We perceive sun moving around the earth, but in fact sun is stationary. The realm of sense organs is limited. Our visible, audible spectrums are considerably inferior to other living species. So, considering the things, our sense organs sense, as the ultimate truth is false method, though they may be helpful to live comfortably in the phenomenal, experimental world.
If we agree the relative nature of existence of the phenomenal things, then an ultimate level of existence is a natural outcome, because every relative posits an ultimate, comparing to which, the relative is called as ‘relative’. Thus, perceptual knowledge that we get from sense organs is useful to get relative nature of things. They help us to communicate and interact with the phenomenal world. But this perceptual knowledge is quite ineffective to realize the ultimate level of knowledge that is superior to the knowledge about phenomenal world.
All perceptual knowledge contains ‘assumption’ as an element in the decision making. We do not perceive a tree as a whole at any time. We can perceive only one side of the tree at a time. We are taking the decision that ‘that is a tree’ without entirely seeing the tree (object). Then how much extend we can believe that perceptual judgment. Reaching in a decision about the ‘whole’ (object) by seeing only ‘a part’ of the object is a faulty method according to strict logic. Furthermore memory impressions, which are vague and oft unreliable, play a significant role in the perceptual judgment.
All of these factors demean the value of ‘constructed’ perceptual knowledge. And there lies an ‘un-constructed’, pure and ultimate knowledge beyond the realm of sense organs.
Problems with the Inference:-
Behind every inference, a perception lies. Without the direct perception of concomitance of the object and its mark, at least once, we cannot infer the existence of one through the perception of the other. That is, without the perception of fire-smoke combination at least once directly, inference of fire from the smoke cannot claim to be valid. Here inference accepts that its basis is perceptual judgment. And the perceptual judgment is not fault free. It is subjected to error. Then if the inference has Perception as the basis, then inference also subject to error. These all points to the untrustworthy nature of our sense perception and the knowledge collected through them. Though this sense perception knowledge is useful in empirical level, it is better not to believe that this knowledge is the ultimate truth.
Carvakas admit perception as the sole means of knowledge, pramana. Are they radical empiricist who pays utmost importance to the perception only? Or do they hold that opinion because of the awareness that ‘the perception is the basis of every inference’ and thus perception is the only ultimate means to knowledge?
Problems with the Verbal testimony:-
It is the presence of authority that raises many Indian philosophical streams to the dogmatic level. Perception and Inference are very well scientific and depend solely on the empirical factors. But Testimony (Sabda) is altogether a different source of knowledge. It assumes that Vedas are divine by origin, i.e., not man-made. Ancient Rishis, who were inspired by some divine bliss wrote Vedas and so, they are infallible and beyond dispute.
Inclusion of verbal testimony in the pramana is justifiable. Inone way or other we get many ideas from books and trustworthy peoples like professors. All such knowledge gathering depends on the authority of verbal testimony only. Transcendental knowledge also can be handover like this way. A Yogi who sits motionless, in deep meditation for some days, can’t be considered as not enjoying any superior bliss that common people can’t enjoy. His/her though level surpasses ours. This is a plain truth.
Why we included authority as a source of knowledge?
Westerners have no literary heritage that is not altered from the time of its inception. Of course, Greeks were there. But Greek thought began at the time when polytheism was prevailing in Greece. Greek philosophy was not the one which is flourished under the current belief system that western world follows. Had the philosophical works of the west has a long standing and un-altered origin which spans to the millenniums, than centuries, then they would be also including those ancient texts, which would be containing many transcendental elements, into their ‘Authority’ list.
 Thus Buddhists included the ‘Comparison’ and ‘postulation’ Pramānas of Advaita Vedanta into ‘inference’
 Buddhists approve testimony in phenomenal world level.
 Internal perceptions are called reflections, in which we immedialy perceive various mental states like pleasure, pain, etc.
 That is, when we have knowledge ‘this is a jar’, we will also have the knowledge, ‘I know the jar’. This is known as self manifest.
 Carvakas has posed some serious challenges in considering inference as a source of knowledge. They point out that there is an infinite regress, present in every inference. That is every inferential judgment demands a previous inferential judgment for its verification. Let us take the case of fire-smoke concomitance. Of course a person, who sees smoke cannot predict the presence of fire int the first instance of the fire-smoke concomitance of his life. He needs a previous instance of fire-smoke concomitance to validate the presence of fire from smoke. And again he needs another fire-smoke concomitance to validate the previous fire-smoke concomitance.. and then again. This process will continue backwards endlessly creating an infinite regress. But if there is a Perception at the beginning of this inference, then the infinite regress is avoidable. So Carvakas argues that inference cannot consider as the source of knowledge. In every inference, a perception lies behind. Every inference presupposes a perception.
 Sruti has superiority about the knowledge related to the transcendental knowledge. But in the relative, experimental world, knowledge that we acquire through sense perception is important. And this sense knowledge may not in any way contrary to the Sruti injections.